[SPARK-5006][Deploy]spark.port.maxRetries doesn't work

https://issues.apache.org/jira/browse/SPARK-5006

I think the issue is produced in https://github.com/apache/spark/pull/1777. 

Not digging mesos's backend yet. Maybe should add same logic either.
I am not sure I understand your point. User still could set this configuration via SparkConf as we just read its value from SparkConf and set it to system properties here.